Spanish posessions
Simply put, if Spain has anything of great value in the Western Pacific, Japan will want it, unless a lot else has changed. Unalloyed greed on one side, along with a percieved lack of the ability to protect what you have on the other, will likely lead to war, or a forced sale, or something that rebalances the greed to vulnerability ratio.
IIRC, Spain in the 1890's had no one it could count on for any sort of overseas help.
So: Spanish-American war, combined with a Anglo-Japanese alliance, could cause Britain to tacitly give Japan the OK to take the islands--and when needed, an excuse can always be found.
Or, if Spain decides to sell, Japan might demand that Spain sell to no one else, since the Philipines in anyone else's hands would be a threat.
A German offer to purchase, or even lease a significant base, would, I suspect, lead Britain to (unofficially) urge Japan to take them.